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[Bug 851722] New: grub2's os-prober reports EMERGENCY corrupt xfs filesystem on extended partition
  • From: bugzilla_noreply@xxxxxxxxxx
  • Date: Fri, 22 Nov 2013 00:14:21 +0000
  • Message-id: <bug-851722-21960@http.bugzilla.novell.com/>

https://bugzilla.novell.com/show_bug.cgi?id=851722

https://bugzilla.novell.com/show_bug.cgi?id=851722#c0


Summary: grub2's os-prober reports EMERGENCY corrupt xfs
filesystem on extended partition
Classification: openSUSE
Product: openSUSE 13.1
Version: Final
Platform: x86-64
OS/Version: openSUSE 13.1
Status: NEW
Severity: Normal
Priority: P5 - None
Component: Bootloader
AssignedTo: jsrain@xxxxxxxx
ReportedBy: jimc@xxxxxxxxxxxxx
QAContact: jsrain@xxxxxxxx
Found By: ---
Blocker: ---


This is for os-prober-1.61-3.1.2.x86_64 required by grub2-2.00-39.1.3.x86_64 .

I upgraded from OpenSuSE-12.3 to 13.1 final. Shortly after reboot, and
again 25 minutes later, something unknown execed os-prober which reports
in syslog probing all partitions, mostly uneventfully except for syslog
reports of negative findings (I have a priority=debug log). /dev/sda4 is
the extended partition on this disc. When 50mounted-tests tries to mount
it (without specifying the filesystem type), most filesystem modules are
not too verbose when they fail to mount /dev/sda4.

However, when mounting is attempted as xfs, it spews out a full call trace
and a lot more, plus a report to all logged-in users, presumably at
priority = emergency. I haven't seen this before: maybe os-prober is
new in 13.1-final (I didn't see the behavior in 13.1-RC1), or maybe
this particular extended partition sets off the bug.

Sooner or later, someone is going to have a partition containing garbage
which looks like a real filesystem -- perhaps even a real filesystem that
got trashed, which you're trying to do forensics on. If the filesystem
module fails to reject a corrupt filesystem, or even one infested
with some kind of virus (think Windows), you could have a really bad
situation.

What I would like the developers to do: I know I'm not going to get
everything I'm asking for here, so I've put the more practical items first.

Desist with os-prober. It's too dangerous and too noisy.

Whatever ran it twice some time after reboot should not be doing that
kind of thing autonomously. Identify it and kill it. At least make
its operation configurable. I don't see any relevant unit files that
could be disabled.

Add a sysconfig parameter, probably in /etc/sysconfig/bootloader, which
tells grub2-install to run os-prober just once, to detect dual-booting.

Alter the logic of os-prober to exclude partitions that are already
mounted, and those with implausible filesystem types like 0x0f (extended).
But you might mount your Windows root partition in Linux; excluding
such things should be configurable.

os-prober should use the "file -s" command and should require it to
definitively identify the filesystem type; unknown or implausible types
(like swap) should be excluded. It should check the filesystem (readonly)
and only then should it attempt to mount it (specifying the type) and then
try to recognize a root partition of an alien operating system.

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